Many medical procedures, including surgery and radiographic imaging, require the stabilization or immobilization of specific body parts. Other medical techniques, such as frameless stereotaxy or delivery of ionizing radiation, require the precise placement of reference (fiducial) markers on or proximate to a body part. Traditional stabilization or positioning techniques for procedures on body parts other than the head include providing padded supports or contoured mattresses. However, when the cranium is involved, the traditional techniques are not completely effective.
One commonly accepted procedure immobilizes the head with a number of invasive fixating pins. Although cranial fixation with invasive pins is adequate for some medical procedures, its use may be undesirable for other applications. For example, typical equipment for implementing pin fixation may be bulky or cumbersome, which can cause access problems during surgery or other medical procedures. As another example, the use of fixating pins involves piercing the skin and embedding the pins into the cranium, which may cause medical complications. In addition, if the patient is an infant or a young child, then the skull is soft and deformable. In such cases, the fixating pins can easily puncture or distort the skull, or may inadequately stabilize the skull for medical procedures. Furthermore, many medical procedures require the patient to be repeatedly immobilized in the same position. With such procedures, repeated pin fixation may be undesirable because of the inherent risk of complications and the inexactness of repositioning the head. Thus, there is a need for an alternative technique for the positioning of the head.
A common medical procedure involves taking radiographic images (such as CT, PET, or MRI scans) of a body part for examination before performing surgery and for use during surgery. Frameless stereotaxy procedures provide localization information to surgeons while they are operating, without the cumbersome equipment associated with frame-based stereotaxy procedures. In addition, modern computer image guided surgery techniques provide surgeons with real-time feedback and images obtained from radiographic imaging procedures during surgery. Fiducial markers are typically utilized during stereotactic and imaging processes to provide reference points for guidance during surgery. Prior art methods typically involve the application of fiducial markers directly to the body part or to a positioning apparatus.
Frameless stereotactic techniques typically require the relative positions of the body part and fiducial markers to be identical during the radiographic imaging and subsequent surgical procedures. However, prior art locating or immobilization techniques often fail to achieve this result. In addition, as mentioned above, although pin fixation may provide adequate immobilization during both imaging and surgery, it is not preferred when the patient is an infant or a child. Therefore, there is a need for an improved locating technique that can accurately position a body part during radiographic imaging and subsequent surgery.